scholarly journals Evaluation of the Biological Control Agent’s Efficiency Against the Causal Agent of Early Blight of Solanum melongena

2021 ◽  
Vol 39 (3) ◽  
pp. 204-209
Author(s):  
Abdulnabi Abbdul Ameer Matrood ◽  
◽  
Abdelhak Rhouma ◽  
Okon Godwin Okon ◽  
◽  
...  
Keyword(s):  
Biological Control ◽  
Polyphenol Oxidase ◽  
Soluble Protein ◽  
Early Blight ◽  
Solanum Melongena ◽  
Alternaria Solani ◽  
Systemic Resistance ◽  
Conidial Suspension ◽  
Antagonistic Fungi

Eggplant, an important vegetable crop in Iraq, faces yield losses due to early blight disease caused by Alternaria solani. Two antagonistic fungi (Aspergillus niger and Purpureocillium lilacinum) isolated from eggplant rhizosphere were tested in vitro (dual confrontation technique) and in vivo (preventive treatments) as potential bioagents against the most virulent A. solani isolates. A. niger and P. lilacinum at 30% conidia/ml exhibited high inhibitory rate (55.11%) against A. solani mycelial growth. Furthermore, these two antagonistic species when applied preventively at 30% of the stock conidial suspension in vivo, reduced significantly disease severity index (<28.41%). Moreover, A. niger (11.98 units/g of soluble protein) and P. lilacinum (8.11 units/g of soluble protein) enhanced the polyphenol oxidase activity. Based on the results obtained by this study, it appears that A. niger and P. lilacinum could be employed as foliar treatments against A. solani to promote eggplant growth and development and induce plant systemic resistance. To control A. solani, it is encouraged to use natural enemies as components in integrated disease management. Keywords: Alternaria solani, biological control, polyphenol oxidase, Solanum melongena, antagonistic fungi

Abiotic Compounds as Inducers of Resistance to Fusarium Wilt in Tomatoes

2018 ◽  
Vol 10 (9) ◽  
pp. 373
Author(s):  
Jose R. M. Campos Neto ◽  
Leonardo de J. M. G. de Oliveira ◽  
Nathalia B. Diniz ◽  
Ivaneide de O. Nascimento ◽  
Antonia Alice C. Rodrigues
Keyword(s):  
Polyphenol Oxidase ◽  
Fusarium Wilt ◽  
Mycelial Growth ◽  
Rating Scale ◽  
Systemic Resistance ◽  
Activity Levels ◽  
Neem Oil ◽  
In Vivo Experiments

To study the effects of resistance inducers used to control fusarium wilt in tomatoes due to the fungus Fusarium oxysporum Schlecht f. sp. lycopersici, we evaluated the effects of ASM (acibenzolar-S-methyl), Agro-Mos, chitosan, Biopirol and neem oil on F. oxysporum f. sp. lycopersici mycelial growth and sporulation and systemic resistance in tomatoes. In vitro experiments comprised evaluations of the products’ effects on the mycelial growth and sporulation of the PDA (potato dextrose agar) growth medium-cultured pathogen. In vivo experiments included product application to tomato plants of the Santa Cruz cultivar that were grown for 25 days on autoclaved soil, followed by determinations of disease severity and peroxidase, polyphenol oxidase and Beta-1,3-glucanase enzyme activity levels, which are related to the process of resistance induction. Pathogen inoculation occurred after 5 days at a concentration of 106 conidia/mL. We evaluated the disease according to a rating scale. Enzymatic activity was determined according to specific protocols. Neem oil controlled pathogen mycelial growth and sporulation, while ASM influenced sporulation. The products reduced the severity of wilt in the plants. We highlight neem oil, Agro-Mos and Biopirol due to their ability to induce significant peroxidase, polyphenol oxidase and Beta-1,3-glucanase expression, respectively.

scholarly journals Lanthanum in vitro control of Alternaria solani and induction resistance mechanism against blight tomato plant

2021 ◽  
Vol 16 (2) ◽  
pp. 153-158
Author(s):  
Antônio Jussiê da Silva Solino ◽  
Juliana Santos Batista Oliveira ◽  
Sergio Augusto Cesnik ◽  
Kátia Regina Freitas Schwan-Estrada
Keyword(s):  
Mycelial Growth ◽  
Culture Medium ◽  
Early Blight ◽  
Resistance Mechanism ◽  
Alternaria Solani ◽  
Plant Diseases ◽  
Guaiacol Peroxidase ◽  
Specific Catalytic Activity

Rare earth elements have been tested in control of plant diseases. Lanthanum (La) was tested in the control of Alternaria solani (in vitro) and tomato early blight (in vivo) using the concentration 0; 0.1; 0.2; 0.4 and 0.8 g L-1. In vitro, the concentration were diluted in V8 culture medium and evaluated for mycelial growth rate index (MGRI) and pathogen sporulation. In vivo, 24 hours after the application of concentration was inoculate the pathogen and 24 hours after the inoculation, leaflets were collected for quantification, the specific catalytic activity and guaiacol peroxidase. The severity of tomato early blight were also analyzed. As 0.27 and 0.28 g L-1 reduces 28% and 50% the MGRI and the sporulation, respectively. Peroxidase and catalase activity was increased by 298% and 151% in tomato treated with 0.5 and 0.4 g L-1de La, respectively. In vivo reduces AUDPC 70% when was applied 0.27 g L-1 La. Lanthanum can be used as resistance inducer in controlling tomato early blight.

Biological control of early blight on potato caused by Altrnaria solani by microbial antagonists

2019 ◽  
pp. 4-10
Author(s):  
Alaa Shahat Aldiba ◽  
Ivan Dmitrievich Escov ◽  
Aleksey Vasilievich Melnikov
Keyword(s):  
Disease Severity ◽  
Mycelial Growth ◽  
Early Blight ◽  
Alternaria Solani ◽  
Cycle Phase ◽  
Dual Culture ◽  
Bacillus Mycoides ◽  
Vitro Assay ◽  
Trichoderma Sp

  Early blight (Alternaria solani) is a potential disease of potato that reduces its production globally both in conventional and tunnel cultivations. Due to variability in pathogenic isolates, prolonged active disease cycle phase and broad host range early blight is very difficult to manage. 8 microorganisms as a bioagent exhibiting inhibitory affects against Alternaria solani, were screened for their activity towards A. solani by a dual culture in vitro assay and in vivo (whole plant) test.in vitro studies indicated that the microorganism’s strains strongly inhibited the mycelial growth of the pathogen. The effect of microorganism’s strains on the mycelial growth (mm) of the pathogen proved to be highest with Trichoderma sp. (0.55) followed by Pseudomonas brassica cearum (0.74) and Pseudomonas jessenii (0.81) on the high concentration (106 cells ml-1) compared to the control (2.30). On the other hand, Bacillus mycoides (2.14) in vivo studies 9 microorganism’s strains were applied in two different application (foliar – soil) and two different varieties (Labella – Romano). The results showed significant reductions in the disease severity (%) with the treatment by Trichoderma sp (2%) followed by Bacillus thuringiensis (3%) and Bacillus mycoides (5%) compared with the control (46%) of Romano variety, while there were a less significant reductions in the disease severity (%)with the treatments compared with the control (16%) of Labella variety . The efficacy of antagonists to suppress the early blight disease varied in respect to the time and type of application.

scholarly journals Occurrence of sdh Mutations in German Alternaria solani Isolates and Potential Impact on Boscalid Sensitivity In Vitro, in the Greenhouse, and in the Field

Plant Disease ◽  
2019 ◽  
Vol 103 (12) ◽  
pp. 3065-3071 ◽  
Author(s):  
Nicole Metz ◽  
Birgit Adolf ◽  
Nicole Chaluppa ◽  
Ralph Hückelhoven ◽  
Hans Hausladen
Keyword(s):  
Succinate Dehydrogenase ◽  
Early Blight ◽  
Solanum Tuberosum L ◽  
Point Mutations ◽  
Alternaria Solani ◽  
Field Trials ◽  
Sensitivity Testing ◽  
Development Of Resistance

The fungus Alternaria solani is the main pathogen causing early blight on potatoes (Solanum tuberosum L.). An increase in the development of resistance to the succinate dehydrogenase inhibitor (SDHI) boscalid, one of the main active ingredients for the control of early blight, has been reported. For this study, monitoring data from Germany were collected between 2013 and 2016 and an increase in the occurrence of A. solani succinate dehydrogenase (SDH) mutant isolates was observed. In addition to the known point mutations in sdh complex II, a new mutation in subunit C was found in German isolates (SdhC-H134Q). SDHI fungicide sensitivity testing was performed in the laboratory, greenhouse, and field. Reduced boscalid sensitivity was shown for mutant isolates (SdhB-H278Y and SdhC-H134R) both in vitro and in vivo. In addition, field trials with artificial inoculation were performed in 2016 and 2017. In both years, fungicide efficacy was significantly reduced after mutant inoculation compared with wild-type inoculation.

scholarly journals Evaluating the Antifungal Activity of Some Traditional Medicinal Plant Extracts against Alternaria solani (Tomato Early Blight Pathogen) in Ethiopia

2022 ◽  
Author(s):  
Meseret Tadelo ◽  
Tamirat Wato ◽  
Tilahun Negash
Keyword(s):  
Medicinal Plants ◽  
Plant Extracts ◽  
Early Blight ◽  
Allium Sativum ◽  
Alternaria Solani ◽  
Significant Inhibition ◽  
Crude Extracts ◽  
Medicinal Plant Extracts

Background: Tomato (Lycopersicon esculentum Mill.) belongs to the family Solanaceae. In Ethiopia, control of early blight is largely dependent on fungicidal application. There is a research need to identify effective botanical extracts to control Alternaria solani that cause early blight of tomato and for evaluation of plant extracts through different solvents on the target pathogen. Methods: In vitro experiment was conducted to evaluate the effectiveness of crude extracts of 16 selected medicinal plants against Alternaria solani. Thus, crude extracts were extracted from medicinal plants with different solvents (methanol, ethanol and petroleum at (25%, 50% and 100%) concentrations. The Alternaria solani was isolated from infected tomato leaves showing early blight symptoms. Evaluation of plant extracts was carried out against Alternaria solani using food poisoned technique on PDA. Result: Results showed that most of the methanolic extract plants were showed significant inhibition of the mycelial growth as compared to ethanolic and petroleum ether extracts. A higher rate of mycelial reduction was recorded by ethanol extracts of Allium sativum at all concentrations (100%) followed by methanol extracts of Allium sativum at 25%, 50%, 100% concentration (90.02%, 97.01%, 100% respectively). The effectiveness of extracts against Alternaria solani depends on use at the higher concentrations and various solvents. For crude extracts that have shown higher inhibitory effects against Alternaria solani in vitro conditions, actual chemical compounds should be identified. Furthermore, it is also important to evaluate these plants on other microbes, study to test in vivo and to assess their real potential field condition wherever early blight is an important disease of tomato.

scholarly journals Prevalence and Impact of SDHI Fungicide Resistance in Alternaria solani

Plant Disease ◽  
2013 ◽  
Vol 97 (7) ◽  
pp. 952-960 ◽  
Author(s):  
N. C. Gudmestad ◽  
S. Arabiat ◽  
J. S. Miller ◽  
J. S. Pasche
Keyword(s):  
Fungicide Resistance ◽  
Early Blight ◽  
Alternaria Solani ◽  
Significant Loss ◽  
Intrinsic Activity ◽  
Wild Type ◽  
Baseline Sensitivity ◽  
Disease Pressure ◽  
Moderately Resistant

Early blight, caused by Alternaria solani, is an important chronic foliar disease of potato (Solanum tuberosum) present every growing season in the Midwestern United States. Most currently grown potato cultivars lack resistance to early blight; therefore, foliar fungicides are relied upon for disease management. Foliar fungicides with high efficacy against the pathogen, such as boscalid, frequently are used under high disease pressure situations, such as potatoes grown under overhead irrigation. Boscalid is a member of the succinate dehydrogenase inhibiting (SDHI) fungicide group and was registered for use on potato in 2005. Baseline sensitivity of A. solani to the SDHI fungicides boscalid, penthiopyrad, and fluopyram using a spore germination assay demonstrated similar intrinsic activity against A. solani with mean EC50 values of 0.33, 0.38, and 0.31 μg/ml, respectively. However, isolates varied in their sensitivity to each of these fungicides, resulting in very low correlations (r) among isolate sensitivity to each fungicide. Resistance to boscalid in A. solani was detected in the states of North Dakota, Minnesota, Nebraska, Texas, Idaho, Wisconsin, and Florida from early blight samples collected in 2010 and 2011. Two phenotypes of boscalid resistance were detected. Approximately 80% of all A. solani assayed were found to have some level of resistance to boscalid with about 5 and 75% of the population moderately resistant (5 to 20 μg/ml) and highly resistant (>20 μg/ml), respectively, to the fungicide. Nearly 99% of all boscalid resistant isolates possessed the F129L mutation in the cytrochrome b gene, indicating that an A. solani population with dual fungicide resistance predominates in the states surveyed. However, A. solani isolates resistant to boscalid remained sensitive to fluopyram, and a large proportion of moderately resistant and resistant isolates were sensitive to penthiopyrad. Disease control data from in vivo trials demonstrated a significant loss of fungicide efficacy when boscalid and fluxapyroxad were used to control moderately and highly resistant isolates of A. solani relative to the control these fungicides provided wild-type isolates. Fluopyram, however, controlled boscalid resistant isolates as well as it controlled wild-type isolates of A. solani. These data will assist potato growers in regions where boscalid resistance is prevalent by assisting them in avoiding fungicides that do not effectively control early blight and in selecting SDHI fungicide molecules that remain efficacious.

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